I have used the bed risers that you mentioned.
They worked fine, but I did find that I wanted them stacked two high, to get the height I needed.
I now have two 2'x6' tables banked together as one large table.
There's a 3rd table I can add on, when I want to sandwich a bigger quilt.
They have adjustable legs.
.... but not as easily adjusted as the one in TallChick's link.
That one looks pretty darned slick!